message("CMake命令行：${cmake_command}")
message("CMake命令行：${CMAKE_COMMAND}")
message("OS：${CMAKE_HOST_SYSTEM_NAME}")


# set(b 我是CACHE变量b STRING "")


function(f)
    set(a "我是修改后的a")
    set(b "我是CACHE变量b" CACHE STRING "")
    set(c "我是c" PARENT_SCOPE)
endfunction()
set(a "我是a")
f()
message("a: ${a}")
message("b: ${b}")
message("c: ${c}")

